1. Field of the Invention
The present invention relates generally to the field of training devices and in particular to training devices wherein simulated smoke is employed. More particularly, the present invention relates to the field of smoke generators for use in firefighting trainers. In even greater particularity, the present invention may be described as a smoke generator which utilizes water and a non-miscible liquid as its generants.
2. Description of the Prior Art
Smoke generators of a general nature are well known. As pointed out in U.S. Pat. No. 2,686,160, issued Aug. 10, 1954, a number of different methods and apparatus for forming oil smokes and fogs have been tried, including: (1) incomplete combustion of the oil; (2) vaporizing an oil in a chamber by indirect heat exchange; (3) spraying an oil against a heated surface for evaporation; and (4) vaporization of a fog-producing oil with steam. U.S. Pat. No. 2,686,160 taught vaporization of an oil spray by hot flue gases for use as screens for military blanketing purposes. In 1958, U.S. Pat. No. 2,850,615 was issued to D. F. Luse et al on a device of type (2) above, wherein glycerin was sprayed on a hot platen to simulate an electrical fire in an aircraft. In 1966, U.S. Pat. No. 3,249,553 was issued to S. B. Steinberg on a smoke generator employing a plurality of venturi spray heads to produce a smoke from dioctylphthalate. Also in 1966, U.S. Pat. No. 3,250,723 was issued to B. C. Fortney on a device of type (1) above. In 1982, U.S. Pat. No. 4,330,428 was issued to E. W. Clifford on a specialized device of type (1) above for use in testing the seals of packages.
These and other methods of smoke production are available for use in training devices; however, due to safety and environmental considerations such as material decomposition and explosion hazards, a very limited number of smoke agent substances are applicable. One such substance, the use of which the applicant is familiar with, is butylated triphenol phosphate, which is reportedly non-toxic and nonflammable. However, a special atomizing nozzle is required to mix the liquid with high temperature air under pressure to produce smoke particles. The heated system presents problems when smoke is ducted because the smoke generant tends to decompose with prolonged heat. Although the smoke is nonflammable, autoignition of the liquid has been observed when the liquid and the high temperature air were inadvertently mixed outside the nozzle.